Class: UOM::Factor

Inherits:
Object
  • Object
show all
Defined in:
lib/uom/factor.rb

Overview

A Factor designates a Unit mangnitude along a dimensional axis.

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(label, abbreviation, base, multiplier = nil, &converter) ⇒ Factor

Creates a Factor with the given label, abbreviations and conversion multiplier or block. The multiplier is the amount of this factor in the base factor. For example, KILO and MILLI are defined as:

KILO = Factor.new(:kilo, :k, UNIT, 1000)
MILLI = Factor.new(:milli, :m, UNIT, .001)

The KILO definition is the same as:

Factor.new(:kilo, :k, UNIT) { |unit| unit * 1000 }

This definition denotes that one kilo of a unit equals 1000 of the units.



22
23
24
25
26
27
28
29
30
 
# File 'lib/uom/factor.rb', line 22

def initialize(label, abbreviation, base, multiplier=nil, &converter) # :yields: factor
  @label = label
  @abbreviation = abbreviation
  @base = base
  @converter = converter
  @converter ||= lambda { |n| n * multiplier } if multiplier
  # add this Factor to the extent
  Factor << self
end

Instance Attribute Details

#abbreviation ⇒ Object (readonly)

Returns the value of attribute abbreviation.



12
13
14
 
# File 'lib/uom/factor.rb', line 12

def abbreviation
  @abbreviation
end

#converter ⇒ Object (readonly)

Returns the value of attribute converter.



12
13
14
 
# File 'lib/uom/factor.rb', line 12

def converter
  @converter
end

#label ⇒ Object (readonly)

Returns the value of attribute label.



12
13
14
 
# File 'lib/uom/factor.rb', line 12

def label
  @label
end

Instance Method Details

#as(factor) ⇒ Object

Returns the multiplier which converts this Factor into the given factor.



33
34
35
36
37
38
39
40
41
42
43
 
# File 'lib/uom/factor.rb', line 33

def as(factor)
  if factor == self or (@converter.nil? and factor.converter.nil?) then
    1.0
  elsif @converter.nil? then
    1.0 / factor.as(self)
  elsif factor == @base then
    @converter.call(1)
  else
    self.as(@base) * @base.as(factor)
  end
end

#inspect ⇒ Object 



49
50
51
52
53
 
# File 'lib/uom/factor.rb', line 49

def inspect
  content = "#{label}"
  content += ", #{abbreviation}" if abbreviation
  "#{self.class.name}@#{self.object_id}[#{content}]"
end

#to_s ⇒ Object 



45
46
47
 
# File 'lib/uom/factor.rb', line 45

def to_s
  label.to_s
end